Doppler ultrasound uses blood flow signals to evaluate arteries and veins. It can detect abnormalities in flow patterns caused by stenosis or occlusion. The key parameters measured include peak systolic velocity (PSV), end diastolic velocity (EDV), and ratios of PSV in different vessel segments. Proper Doppler technique optimizes settings for sample volume placement, angle correction, and velocity scales. Common carotid artery (CCA) and internal carotid artery (ICA) waveforms are analyzed and compared bilaterally to detect asymmetries indicating stenosis. Degree of stenosis can be estimated from increased PSV ratios at and above areas of narrowing. Ulcerated or heterogeneous plaques on ultrasound also suggest unstable lesions.

1. DOPPLER STUDY
GENERAL BASES

2.  Blood flow
 1-laminar central flow.
 2-smooth with no turbulence.
 3-physiological turbulence.
-bifurcation.
-widening.
-arching.

3.  Probe
 Methods
 1-Audible
 2-Duplex
 3-Triplex

4. Types of Doppler ultrasound
 -Color Doppler.
 -pulse wave.
 -Continous wave.
 -Power Doppler

5.  Arterial –Triphasic ( dec early dias due to inc
peripheral resis.
 Inc late dias due to re elasticity
 -biphasic ( due to re elasticity)
 Venous –monophasic (cardiac and respiratory
modulations).

7. Triphasic Monophasic – hyperemic
flow

9. Before stenosis- normal Distal to stenosis-parvus-tardus
At site of stenosis- incr velocity
spectral broadening (mosaicing)

10. In case of partial arterial stenosis
If the stenosis is < 50%, the speed is normal.
50% stenosis, velocity will be 1.5-2 time.
50-75% 2-4 time.
>75% >4 time..

11. Color steer box
It should be as small as and superficial as possible.
Change angle of insonation between 30-60 to get
less error.
If not sufficient– angulation of the probe.

16. Adjust system gain;
Amplification of signal to provide good quality
Decrease Doppler gain ---inadequate color saturation
(Doppler mopping)
Increase Doppler---noise
Adjust color velocity scale (range of velocities used)
If aliasing --- increase
If abscent flow---decrease

19. Sample volume
The sample site from which the data obtained.
Used for pulse wave, not for continous wave.
It should be
Narrow zone 1/3 -2/3 of blood vessel diameter.
To decrease spectral broadening
Central in position– to acquire highest speed of flow.
If peripheral –slow motion of blood and vessel wall motion
detected.
Angle correct
Trying virtual to be inside the vessel (parallel to the lumen,
never exceed 60 degree.)

24. Pulse repetition frequency:
Range of velocities used
Spectral Doppler scale;
Same as color gain
Wall filter; not commonly used
Filter motion of wall motion in case of peripheral volume sampling
Frame rate;
Try to be high
Number of refreshing the images/sec
NB; flow direction; above base line toward the probe.
Below base line – away from the probe.

32. Adv;
Very sensitive to very sluggish flow
No aliasing
Angle independent
Useful in tortuous vessels
Disadv;
Don’t provide flow velocity.
Unidirectional.

34. Aliasing
Inability of device to
detect high blood flow
in PWD
Solution
Incr PRF
Down ward base line
Broadening of spectral
window
Spectral window ;black
Area under the curve(it
should be open)
1- wide sample volume;
narrow sample volume
2- high Doppler gain;
decrease gain
Turbulent flow
Physiological and
pathological.
Color Doppler inaccuracy
Over or under saturation
Of color in blood vessel or
abnormal color pattern
Causes;
1-Inadequate Doppler gain
--Doppler mopping
2- incr Doppler gain
Noise
3-inadequate steering
4-Aliasing; incr PRF

35. Resistive index=S-D/S
Pulsatility index=S-D/Mean
S/D; D/S
Acceleration index-change in distance between beginning
Of systole to the peak of systole cm/s
Normal value >3.8cm/s
Acceleration time-length of time in sec from onset of systole to the
peak.
Normal value <0.07 sec.

38.  Patient Position
 supine or semi supine
 head slightly hyper‐extended
 rotated 45°away from the side being examined.
 Higher‐frequency linear transducers (7 MHz)

39. Vessels should be imaged as completely as possible
•Caudal angulation of the transducer in the supra-
clavicular region and cephalic angulation at the
level of the mandible.
•Assessed both in gray scale and colour Doppler
settings.

40.  Limitations
 short muscular neck.
 a high carotid bifurcation.
 tortuous vessels.
 calcified shadowing plaques.

41. Scan both in transverse and longitudinal plane.
•Starting from proximal most CCA, bulb, ECA and
ICA.
•Distal carotid ‐2 cm from the bulb.
•ICA or ECA ?
Large in caliber, posterior and lateral
low resistance wave form (not reliable)
no branches
no cluttering with temporal artery tapping.

42. Color Doppler Sampling Window
 also known as the color box
 The size is adjusted to include all regions of
interest.
 Adjustment of the angle‐by changing the box
angles from left to center or right
 angling the transducer to ensure that the
Doppler angle is less than 60°to the direction of
blood flow.

44.  If the Doppler angle is small or more than 60 degree
‐small error in the estimated velocity.
 preferred angle of incidence is 45°±4.
 The optimal position of the sample volume gate
in a normal artery is in the mid lumen parallel to the vessel
wall
 in a diseased vessel, parallel to the direction of blood
flow
should not be placed on the sharp curves of a tortuous
artery ‐falsely high velocity reading.
 Should not be placed too close to the vessel
wall‐spectral broadening.

46.  Spectral broadening results from turbulence in the
blood flow.
 Spurious spectral broadening
 a large Doppler angle
 a sample volume gate located close to the vessel wall
 a high Doppler gain setting
 The size of the gate is normally ‐between 2 and 3 mm.
 too small (1.5 mm) ‐the Doppler signal may be missed
too large >3.5 mm ‐spectral broadening

47.  If set below the mean velocity of blood flow,
Aliasing throughout the vessel lumen.
 set significantly higher than the mean velocity of
blood flow, aliasing may disappear resulting in a
missed stenosis
 In a normal carotid US examination, the color
velocity scale should be set between 30 and 40
cm/sec(mean velocity).

49.  The color gain should be set so that color just
reaches the intimal surface of the vessel.
 If the color gain setting is too low, trickle flow may
go undetected.
 If a color gain setting is high, “bleeding” of the
color into the wall and surrounding tissues ‐limit
visualization of the plaque surface

51. PDI may provide increased sensitivity to visualize
the continuity of blood flow in arterial stenosis

52.  Defined as a localized protrusion from the
wall into the lumen with an area 50% greater
than the intima ‐media thickness of
neighboring sites.
 low and high echogenic plaque.
 heterogeneous or homogeneous.
 regular (smooth) or irregular.

53.  If more than 20% of the plaque echogenicity differed
from the echogenicity of the rest of the plaque by
two or more echogenicity grades –is heterogenous.
 When height variations between 0.4 and 2 mm
along the contour of the lesion –is irregular
 Ulcerated plaques‐recesses in the contour of the
lesion at least 2 mm in depth, with a well‐defined
back wall at the base showing flow.

55.  Heterogeneous plaques and ulcerated
plaques are unstable or friable.
 Potential for embolicTIA and cerebrovascular
accidents.

56. Fissuring or ulceration in the plaque

58.  Class I,homogeneous texture, uniformly hypoechoic
 Class II,heterogeneous texture, predominantly
hypoechoic
 Class III,heterogeneous texture, predominantly
hyperechoic
 Class IV,homogeneous texture, uniformly
hyperechoic
 ClassV,unclassified calcified plaques

59.  After optimizing the setting ****
 Measure the velocity –PSV and DV
 Proximal and distal CCA
 ICA and ECA
 Vertebral artery
 Wherever stenosis present –
 at stenosis
 proximal to and distal to stenosis
 Compare bilateral carotid velocities –symmetric or asymmetric

60. combination of ICA and ECA patterns,
•intermediate amount of continuous forward diastolic flow
•a sharp systolic upstroke and thin spectral envelope
•flow below the baseline or filling in of the spectral window normally should not be
seen

61. a low‐resistance waveform pattern
•systolic peak should be sharp and the spectral envelope thin
•continuous forward diastolic flow
•the systolic peak may be slightly blunter than the systolic peak of the ECA

62. the systolic upstroke is sharp
•the spectral envelope is thin.
•reduced to no diastolic flow
•diastolic flow should be symmetrical bilaterally
•Transient reversal in early diastole (characteristic early diastolic notch ) ‐a normal finding

64. Pattern
•Systolic contour
•Diastolic pattern
•PSV
•DV
•ICA PSVs / CCA PSVs ratio
•Compare Right and Left side

65.  Either low or high PSVs.
 abnormally high‐resistance waveform,
 an abnormally low‐resistance
waveform.

66.  A normal CCA PSV should be in the range of
approximately 60 –100 Cm/s
 •IF less than this, examine opposite side
 Symmetric Asymmetric
 (near normal)
 Low cardiac output
 Evaluate further
 A velocity difference of >20 cm/sec between the
right and left is abnormal.

67.  Proximal stenosis (brachiocephalic)
 Parvus ‐tardus waveform or normal pattern
but asymmetrical PSVs.
 Distal stenosis (carotid bulb level)
 High resistance wave form

68. Innominate artery occlusion

69. High-resistance waveform in CCA
 High‐grade ICA stenosis or occlusion
 (externalization of the CCA)
 Distal waveforms should be assessed (support the
diagnosis)
 EXCEPTION IF
 ???
 is bilateral and low PSVs indicates
 Aortic stenosis
 Severe cardiac failure

70. CCA
ICA

71. ICA OCCLUSION

72.  The ratio of the highest PSV at the CCA
stenosis divided by the PSV 2 cm proximal to
the stenosis should be calculated.
 PSVcca at stenosis/PSVcca prox.
 If the ratio is 2 or more and less than 2.99
‐stenosis of 50% or more.
 If the ratio is 3 or more stenosis of 75% or
more.

73. LOCAL CCA STENOSIS

74. Unusual finding in Case of CCA
occlusion .Reversal of flow in ECA
and low resistance and low PSVs in
ICA as it is fed by collaterals.
This is to maintain the ante grade
flow in ICA.

77.  If the stenosis is unilateral, there is marked
asymmetry in the systolic contour of the
waveforms of the right and the left CCAs.
 If the stenosis is central, such as with aortic
stenosis, the waveforms are affected
bilaterally.

78.  Normal is ‐low resistance with high diastolic
pattern.
 Most common site is ICA origin –plaque
extending from the bulb.
 High resistance pattern in the ICA‐Stenosis
distally.
 PSVs raises ‐Significant stenosis

82. String sign -NearTotal Occlusion

83. Total occlusion

84. So assess ICA
•In gray scale for amount of luminal narrowing
•Assess velocities in proper settings
•Should assess PSV, EDV and ratio of PSVs in ICA
and CCA
•Assessed proximally, mid and distally.
•If no color flow demonstrated in a tight stenotic
segment even in power Doppler confirm with
other modality
•Assess opposite ICA for compensatory flow

85.  Confirm the ECA
 Is there any reversal of flow
 Is there any internalization

86. Mid Systolic Retraction –Pulsus Bisferience

87.  PULSUS BISFERIENCE
 ‘‘beat twice,’’
 Characterized by two systolic peaks with an
interposed mid systolic retraction
 Seen in
 AR with or without concomitant AS
 Hypertrophic obstructive cardiomyopathy
 Occasionally, may be seen in healthy, athletic,
young individuals or in older patients.

88. Alternating systolic peak -Pulsus Alternans

89.  PULSUS ALTERNANS
 •Alternating peak systolic heights on sequential beats in
a regular normal sinus rhythm.
 •Clinical conditions
 Intrinsic myocardial disease
▪ Ischemia
▪ Cardio -myopathies
 Valvular heart disease

90. WATER HAMMER PULSE

91.  water hammer pulse’’
 In aortic regurgitation –reversed early diastolic
flow in both CCAs with elevation of PSV and a
sharp systolic upstroke
 Depending on the severity, the reversal of flow
may be limited to early diastole with
normalization of forward flow in end Diastole
or may persist throughout diastole.

93. DISSECTION
 •Trauma ‐seat belt injury or repetitive trauma.
 •Occasionally, spontaneous and isolated to the carotid
arteries in Marfan syndrome, Ehlers‐Danlos syndrome,
fibromuscular dysplasia, hypertension, or drug abuse
 •Also ‐direct extension of an aortic dissection.
 •Rare but, dissection of the ICA is the most common
cause of stroke in young patients.
 •Most ICA dissections occur at the level of the carotid
bifurcation.

94.  Wave pattern is extremely bizarre in configuration:
low PSV velocity with a highly irregular waveform
contour with many spikes or fluttering with reversed
or bidirectional of flow, such that it may be difficult to
distinguish systole from diastole
 •an intramural hematoma, causing a long‐segment
tapering of the ICA without a break in the intima
 •The residual lumen may be narrowed markedly,
creating a ‘‘string sign.’’

95.  Thrombosis of the false lumen ‐mimic
stenosis
 The waveform may be indistinguishable from
a stenosis except that typically it extends
over a much longer segment and often no
plaque is visualized.

96.  The presence of early diastolic flow reversal
in the ipsilateral CCA
 •reduced peak systolic and diastolic velocities
in the ipsilateral ICA
 are non‐specific, but warrant a search for a
cause of increased peripheral vascular
resistance.

97. Echogenic flap Hematoma with dissection

99. GREATTHANKS